Purification of alcohols



Feb. 21, 1950 D. M. KIMBLE l 2,497,997

PURIFICATION 0F ALCoHoLs Filed March 4, 1946 Patented Feb. 2l, 19502,497,997 PURIEIcArIoN or ALcoHoLs Dwight M. Kimble, Los Angeles,Calif., assignor to Union Oil Company of California, Los Angeles,Calif., a corporation of California Application March i, 1946, serialNo. l651,986-

.e claims.A (o1. 26o-'617) The invention relates to the treatmentofcorrit plex mixtures of organic` compoundscontaining therein a tertiaryalcohol and particularly a ter- Atiary naphthenic alcohol. Moreespecially the invention relates to the separation of such tertiary ,A 5"naphthenic alcohols, either as an alcohol rich fraction or as usefulderivatives thereof.

Such processes in organic syntheis as oxidation, reduction,dehydrogenation, dehydration and ether formation are Well known and fromsuch 1 0 vprocesses there are obtained complex mixtures,

the purification of which is contemplated in the present invention. Morespecifically the invention provides means for purifying the productsresolution ofthe mixture resulting fromthe ox-il dation of naphthenichydrocarbons. Such a mix- `ture will includehydroperoxides,secondary andtertiary naphthenic alcohols, ethers and ketones, predominantlynaphthenic in. character, and I have found this mixture diflicult toseparate by l'fractionation even at reduced pressures as a result of thedisturbance of the normal vapor pressure equilibrium of these` compoundsby azeotrope formation, hydrogen bondingor someother mechanism difficultto ascertain.

`Vlt is .therefore a .primary object of the present invention toseparate secondary and tertiary naphthenic alcohols from ketones ofsimilar boil- 'from the oxidation of naphthenic hydrocarbons, 1'5 `ingpoint and particularly from naphthenic `from the reduction of highboiling ketones and particularly high boiling naphthenic ketones, from'the oxidation or dehydrogenation of high boiling naphthenic alcoholsand from the partial dehydration of glycols which last named processresults ,1go

in the formation of monohydric alcohols and cyclic ethers of similarboiling points. Thus, I contemplate the treatment of mixtures ofsecondary and rtertiary naphthenic alcohols, secondary and tertiarynaphthenic alcohols containing ketones, secg5 vondary and tertiarynaphthenic alcohols contain- -ing ketones and ethers including theepoxides, .secondary and tertiary naphthenic alcohols containing ketonesand hydroperoxdes, secondary -and tertiary naphthenic alcoholscontaining hye30 droperoxides and ethers, secondary and tertiary"fnaphthenic alcohols containing ketones, hydroperoxides and ethers, andthe like. The presence of a secondary alcohol in these mixtures is inmost 'cases the normal result of the processes from,.; :35

which these mixtures originate, but the invention `is equally applicableto the-separation of mixtures f of the above types in whichsecondaryalcohols; are

not present.

All of the above mentioned processes amimpar- ,5,40

-ticularly that of the oxidation of naphthenichydrocarbons are facedwith a number of chemical resolution problems. Each resolution has inthe past involved a costly process including such `operations as steamdistillation, precipitation, ltration, precise fractionation, or thelike. These processes present many operational difficulties as a resultof the closeness of the boiling points of the `'various' componentswithin the complex mixture to be resolved, the tendency of certain ofthe com-@15o .pounds contained therein to decompose at the necessarytemperatures of processing?v and .the :effectsof hydrogen bonding orazeotrope formaftion between various components of the mixture.

aprocess for the separation of secondary and tertiary naphthenicValcohols of similar boiling 'points from each other.

Yet another object of the present invention is "a provision of a processfor the concentration of a peroxide-containing mixture resulting fromthe oxidation of naphthenic hydrocarbons by the removal therefrom of thesecondary and tertiary `naphthenic alcohols formed in the process.l

Correlatively, and as a modification of the process employed toaccomplish the above objects, the

present invention further contemplates the preparation of the naphthylesters of the amphoteric metals including particularly boron, aluminum,arsenic and tin. Y

It is also 'an object of the present invention'to eifect the resolutionof the above-described mixtures in such a manner that organicesters fof'tertiary naphthenic alcohols having useful .plastil vcizingcharacteristics Vwill be formed. I 1

'l lOther. objects and nadvantages-of the present *invention vwill`become apparent .tothose skilled in the art as the description thereofproceeds.

The processes and modifications of' myinven- Vtion as claimed herein areillustrated in the accompanying drawing, which is in the form of a iiowdiagram.

According to the ,present Ainvention the above contemplated objects areaccomplishedv by 1. `"a process which involves the alcoholysis of thesecondary and tertiary naphthenic alcohols contained in the complexmixtures hereinbefore discussed followed by distillation of theresultant mixture to yield two fractions; one rich in the ketones,peroxides; and materials boiling below the esters formed in thealcoholysisreactiomand the rother rich in these esters. latter effect isparticularly apparent inathe- "55 Alternative procedures arated from theperoxide-containing mixtureby alcoholysis as above described leaving theperoxide contaminated only by theketones contained in the originalmixture. In this regard, I have found that in a crude oxidation productfrom which the unreacted hydrocarbons have been' removed there isapproximately twice the concentration of mixed secondary and tertiarynaphthenic alcohols than of the ketones. Thus,I in a typical concentratethere will be approximately 60% of naphthenic hydroperoxide, 25% to' 30%of" secondary and tertiary alcohol, and to of ketones predominantlynaphthenic in character; Therefore', *byl 'the removal of the yalcoholsfrom this mixture by the process of my invention the peroxide'contentmay be increased from approximately 60% to from 80% to V85%.Alternatively, by the method hereinafter described the peroxides may bedecomposed in the process of alcoholysis to' yield additional naphthenicalcohols. This modification will be particularly desirable when thealcohols constitute the primary product sought.

The alcoholysis step of the process is carried out at temperaturesranging from about 80 C. to about 150 C. and at pressures in the rangeof about l0 mm. to about atmospheric in the presence of an organic esteror a metal alccholate of an alcohol boiling below the alcohols to beseparated from the crude mixture. In this respect I prefer to employ, toaccomplish the ester exchange reaction, the estersof the amphotericmetals and particularly borony and aluminum with low boiling primaryaliphatic alcohols such as ethyl aluminate, propyl borate,` butylborate, butyl aluminate, and the like. Many of the metal naphthylatesformed in the alcoholysis reaction are valuable as'vsuch, withoutsubsequent hydrolysis, as intermediates for organic synthesis, and it isWithin the contemplation of. myv invention toisolate these naphthylates`for this-purpose.

Because of the ready availabilityof aluminum y it may find wider usagethan the boron in the formation of the lower. boiling: esters necessaryIto the alcoholysis reaction; In addition. to this: advantagefwe havevfound that in many instances the formation: and usage of' the lowerboiling alcoholates is unnecessary for aluminum metal maybe used. assuch to Ves'terify the secondary and tertiary naphthenic alcoholswithout the necessity of going through the ester exchange reaction.Thus, aluminum powder or shavings may be added directly to the complexmixture con- .tain'ing either secondary or tertiary naphthenic alcohols'or both, and by maintaining'the mixture at a temperature of 30 C. orhigher at reduced or atmospheric pressures the aluminum alcoholates ofthe secondary and tertiary alcohols mayl be formed. In this manner thetertiary alcohols may be reacted with aluminum in one of two ways, viz;(1f) inthe presence of the aluminum alcoholatecf alow boiling alcohol;or (2)l in the presence of aluminum metal. anda primary alco- 4 hol thatdoes not interfere with the boiling point separability of the mixture.

The alcoholysis step of the process may be employed to accomplish diversends. Thus the difference in the rate of esterication or ester exchangeexhibited by secondary and tertiary naphthenic alcohols may be utilizedto selectively esterify'secondary alcohols preferentially to thetertiary alcohols thus providing means of separating these alcohols froma mixture containing both. Alternatively the alcoholysis may becariiedsubstantially to completion whereby both the secondary andtertiary naphthenic alcoholates are"A formed in which case thesealcoholates may be'separated from' other organic components in themixture such as naphthenic ketones, naphlthenic hydroperoxdes, alicyclicketones, ethers,

vboilingmetal alccholate or a metal but-notin the presenceof-'th'ecorrespondingacid, for. ifv thev acid ywere to be' employed directly,dehydration of these alcoholsv would result rather than the desiredalcoholization.

In anotherl alternative methodofprocedurerthe ester exchangev may becarried out. at conditions of? sufficient. severity to effect thedecomposition of any naphthene peroxide in. the mixture. Classicalmethods of hydrogenation of such peroxide containingmixtures in thepresence. of a catalyst or reduction with ferrous sulphate or similarmaterials cause a large part of the peroxide. to bedecomposed to lowermolecular weight products I have found that. by carry'- ing out theester exchange reaction of my'invention .atx conditions:adapted to'decompose these peroxides that the' primaryl products ofdecomposition-y are the correspondingl alcohols which in the casey ofnaphthenic peroxides or hydroperoxideswill benaphthenic alcohols. Thismethod of procedure resultsin a distinct advantage over those of theprior art inasmuch as theY alcohols, which are'more'desirablecompounds.. areA formed, and'1 these alcohols being predominantlysecondaryand tertiarynaphthenic alcoholsfmay be separated from otherOrganic'compounds in themixture together with the secondary and tertiarynaphthenic alcohols originally present therein. Thus, by carrying outthe. process at temperatures betweenabout 90 C. to 11.0'C..the peroxidewill bel decomposed to the corresponding alcohol, whereas attemperatures from 80' Cl to 1005 C.

' the ester exchange mayy be' accomplished without appreciabledecomposition thereof. The apparentV overlapping of these temperatureranges is due to the difference i'n conditions necessary orpermissible-dependent upon the concentration of peroxide in the mixture.Thus; the lower the concentration of peroxide the higher the temperaturenecessary to' effect the decomposition thereof or correlatively. thehigher the permissibletemperature without decomposition. Which view istakenis dependent uponthe end: products sought. @bviously the conversesituation also exists.

Following the alcoholysis step of the process, regardless of the method.of. accomplishment thereof', the reaction mixture is flash. distilled toremove lower boiling. organicy components from thee naphthenicalccholate. For example, the

original mixture comprises the products from the adapted to preventl thedecomposition of the` V peroxide there will be `separated from thenaphthenic alcoholates in this iiash distillation the ketones andperoxides present in the mixture together with lower boiling impurities.On the other hand, if the alcoholysis is carried out under conditionsadapted to decompose the naphthenic peroxide to naphthenic alcoholswhich are subsequently esteried, the primary component to be separatedtherefrom will be the ketones present in the original mixture. i i

Turning now to the residue from tillation, which comprises essentiallythe alcoholates of naphathenic alcohols and; in lsome cases residualhigher boiling organic compounds, several alternative procedures may befollowed. In the simplest of these, the alcoholates may be hydrolyzed toreform the corresponding secondary and tertiary naphthenic alcoholswhich thereuponmay be separated from any residual material bydistillation. The hydrolysis of these alcoholates may be readilyaccomplished with water f to form the alcohols or alternatively otherwaterlike materials may be employed to form other compounds. Suchalternative hydrolyzing agents for example may include ammonia, liquidhydrogen cyanide, phosphine, and the like, andthe alkyl A analogs ofsuch compounds. Products from the hydrolysis will in any case result inthe formation of the metal-containing acid, the metal oxide, or organicacid, depending upon the composition of the alcoholates and not upon thehydrolyzing agent. On the other hand, different compounds will be formedwith the naphthenic portion of the alcoholates dependent upon thehydrolyzing agent employed. Water, of course, will result in theformation of the corresponding naphthenic alcohols, ammonia in theformation ofcorresponding amines, hydrogen cyanide in the formation ofcorresponding'nitriles, phosphine in phosphides, and so on.

l `The hydrolysis of the alcholates is accomplished by treatment of thealcoholate concentrate, resulting from the distillation of the productsof alcoholysis, with the desired hydrolyzing agent which may -be any ofthe above-described compounds or similar compounds at temperatures inthe range of about 25 C. to about 200 C. and at pressures in the rangeof about l`to about 500 atmospheres. The products from the hydrolysisthe above dismay be distilled from the unreacted'rmaterialto Y givesubstantially pure compounds or fractions of similar compounds. Thus ifthe alcoholates to be hydrolyzed consist of a mixture of secondary andtertiary naphthenic alcoholates, the products of hydrolysis with waterwill comprise the corresponding naphthenic alcohols and I have foundthat by the distillation of this hydrolysis product an alcohol fractionof a purity of 95% or more may be obtained. In such a case this alcoholyproduct will comprise a mixture of secondary and tertiary naphthenicalcohols.. In this regard the relative proportions of these two types ofalcohols in the fraction will be dependent upon the method ofalcoholysis employed. Thus, if the ester exchange is carried out so asto preventthe decomposition of the naphthenic peroxides the normal ratioof secondary alcohol to tertiary alcohol is in the range of about l toabout 3 or 4. However, if the alcoholysis is carried out underconditions adapted to promote the decomposition of the naphthenicperoxide to naphthenic alcoholsv the-ratio of secondary naphthenicalcohols to 'tertiary naphthenic alcohols will be in the'l range ofabout l` to l5. In either case the alcohol fraction `obtained may betreated in an identical-manner as above described to effect theseparation of the secondary from the tertiary naphthenic alcohols; i.e., by selective alcoholization of the more rapidly esteried secondaryalcohol.

Alternative procedures may be followed in the treatment of thealcoholate fraction obtained from the'flash distillation of the productsof the alcoholysis step. In one alternative the naphthenic alcoholatesmay be advisedly used, as such, as intermediates for organic synthesisin whichcase the process is terminated at this point eliminating thenecessity of hydrolysis, etc.

In another method of 'operation the products of alcoholysis may betreated prior to distillation with an oxidizing agent such as ferricsulfate,

cupric sulfate, or the tertiary hydroperoxide itself, which may becontained inthe original mixture in the event that such mixture wasderived from the oxidation of naphthenic hydrocarbon. In this treatmentthe ketones present will remain as such Vand in addition any secondaryalcoholates, derived from the secondary alcohol which probably arose inthe rst instance from the reduction of the ketones, will be converted toketones. By proportioning the oxidizing agent, such as the peroxide,against the secondary alcohols present the end products will comprisepurev tertiary alcoholates and ketones which may then be separated byflash distillation to remove the lower boiling ketones, and the puretertiary alcoholates may be hydrolyzed or employed as such as'hereinbefore described. In order to catalyze or4 increase the rate ofthe above oxidation reaction it may be desirable to add small amounts oreven molar amounts of an aluminum alcoholate of a low boiling alcohol.

. It is also possible to use a high boiling ketone as the oxidizingagent in the above modified procedure. As a result this high boilingketone would be reduced to an alcohol simultaneously with the oxidationof the secondary alcohols to the ketone.

`Where the tertiary peroxide is to be used as the oxidizing `agent thesecondary alcohols present in the mixture as well as any primaryalcohols, which might be in certain mixtures to be treated, will beoxidized to the corresponding acid or aldehyde and ketone depending uponthe conditions of oxidation employed and the thus produced carbonylcompounds will be freed from the metal complexes normally resulting fromthe oxidation of l the alcoholates by the teritary alcohol produced fromthe correlative reduction of the peroxide. These carbonyl compoundswould then b'e distillable from the reaction mixture as above indicated.This process provides a means to convert 1,3 and 1,4-glycol to thediketones which find usage in the production of barbiturates.

The process of my invention also provides means for preparing theorganic esters of the tertiary naphthenic alcohols which have heretoforebeen diflicult to prepare due to the ease with which these alcoholsdehydrate. I have found that these esters can be readily formed by thetreatment of the metal alcoholate with an organic.;acid, organic ester,or acetic anhydride. Thus the naphthyl borates or aluminates formed inthe alcoholysis of the tertiary naphthenic al- 75 cohols may be treatedwith acetic anhydride to Produce the acetate esters of A these tertiary.naphthenic alcohols. In such a process it wasv observed thatsubstantially no olens were formed. In this reaction, assuming thealcoholatel to bev vtreated to be a naphthyl boratethe boron would beobtained either acetylatedas the triacetyl boron or` as borontrioxide'dependent .upon the stoichiometric proportions of the reactantsemployed. In addition, for the acids of higher` molecular weight, theacetyl chlorides:` are suitable acetylating agents in which case agaseous product would be formed such as boron trichloride. TheVformation of s-uch a gaseous product would have the effect ofminimizingA any'purification difficulties by virtue ofV theease ofremoval of such gaseous product from the reaction. mixture. T-heseorganic esters of the tertiaryv naphthenicalcohols are` valuableas-plasticizers, and also in some cases as fungicides -and insecticides.

Broadly, therefore, the process ot myv invention contemplates andprovides means for the resolution of complex fractions of organiccompounds containing secondary and tertiary naphthenic alcohols or`simply tertiary alcohols tgetherwith such, compoundsv as the peroxides,hydroperoxides, ketones, of eitherr naphthenic or parainnic character,ethers, and the like. The resolution is accomplished primarily bytheal.- coholysis of this mixture either vwith a-lower boiling aicoholester of an amphotericV metal and particularly with aluminum or borate.ester of the lower boiling alcohols or with aluminum metal itself,whereby the alcoholates formed may be separated as'such from anyketones, peroxides or other compounds remaining in the mixture, whichbarring decomposition thereof to alcohols will be unaiiected by thealcoholysis.I .In-this regard, methods of alcoholysis have beendisclosed which permit the decomposition of naphthenic peroxides,contained in many such mixtures, to corresponding secondary or tertiarynaphthenic alcohols: i. e., the alcoholysis lmay be accomplished toproduce either the peroxide as such or alcoholates derived from thealcohols resulting from the decomposition of these peroxides. Thealcoholatesl separated from the other organic compounds in the mixture,may be usedas lsuch as chemical intermediates, may be hydrolyzed to thecorresponding alcohols, may be hydrolyzed with compounds. other thanwater .to formnitriles, amines, or the like, or may be treated withsuitable oxidizing agents to separate. the secondary from the tertiaryalcoholates; by the mechanism of oxidation of the secondary alcoholsinany of which alternative proceduresthe resultant products may beobtained in substantially pure form by simpley distillation. Thus theinvention asherein described` and claimed comprises any and all of theseprimary procedural methods together with the modifications thereofherein disclosed.

Having described my invention and realizing that many modicationsthereof will' occur to those skilled in the art without departing-fromthe contemplated objects or the described methods of my invention, I'claim:

1. A'proc'ess for the purification of a mixture of secondary andtertiary naphthenic alcohols, naphthenic peroxide and ketones to recovertertiary naphthenicalcohols therefrom which comprises contacting saidmixture ata temperature between about 90 C. and 110 1C. withani a1-coholate of an amphoteric metal and a-primary alcohol, said primaryalcohol having a boiling point. below that of the alcohols contained insaid complex mixture, whereby vsaid secondary and tertiary naphthenicalcohols are converted to the corresponding naphthenic alcoholates, thesecondary alcoholates are oxidized to the corresponding ketones byreaction with said naphthenic peroxide and said naphthenic peroxide isreduced to the corresponding naphthenic alcohol', which last namedalcohol is converted to the corresponding amphoteric metal naphthenicalcoholate by reaction with said primary alcoholate, separating theresulting tertiary naphthenic alcoholates from the reaction mixture andhydrolyzing said separated tertiary naphthenic alcoholates to form thecorresponding tertiary naphthenic alcohols.

2. A process according to claim 1 in which the metal is aluminum.

3; A process according to claim 1 in which metal is boron.

4. A process according to claim 1 in which ad'- ditional naphthenicperoxides are added following the contacting of the complex mixture withan alcoholate of an amphoteric metal and secondary alcohol in an amountsufficient to completely oxidize the secondary naphthenic4 alcolatespresent.

5. A process for recovering tertiary naphthenic alcohols from a complexmixture containing sec'- ondary and tertiary naphthenic alcohols,ketones and tertiary naphthenic hydroperoxides which comprisescontacting said complex mixture at a temerature between C. and 110 C.with analcoholate of an amphoteric metal and a primary alcohol, saidprimary alcohol having-a boiling point below that of the secondary andtertiary naphthenic alcohols, which contacting operation converts'saidsecondary and tertiary alcohols into the corresponding amphoteric metalnaphthenic alcolates, the secondary naphthenic alcoholates beingoxidized bythe naphthenic hydroperoxides present in said mixture therebyconverting the secondary naphthenic alcoholates to ketones andconverting said' naphthenichydroperoxides to tertiary naphthenicalcohols, which last named alcohols are converted to the correspondingamphoteric metal naphthenic alcoholates by the primary alcoholates,distilling the resulting reaction mixture to vaporize ketones andprimary alcohol thereby leaving tertiary naphthenic alcoholates as adistillation residue.

6. A process according to claim 5 in whichadditional naphthenicperoxides are added following thel contactingof the complex mixture withan alcoholate of an amphoteric metal and Asec-- ondary alcohol in amountsuficient'to completely oxidize the secondary naphthenic alcoholates.

DWIGHT M; KIMBLE.' l

REFERENCES Cirri)v The following references are le of this patent:

UNITED STATES PATENTS of record in the

1. A PROCESS FOR THE PURIFICATION OF A MIXTURE OF SECONDARY AND TERTIARYNAPHTHENIC ALCOHOLS, NAPHTHENIC PEROXIDE AND KETONES TO RECOVER TERTIARYNAPHTHENIC ALCOHOLS THEREFROM WHICH COMPRISES CONTACTING SAID MIXTURE ATA TEMPERATURE BETWEEN ABOUT 90*C. AND 110*C. WITH AN ALCOHOLATE OF ANAMPHOTERIC METAL AND A PRIMARY ALCOHOL, SAID PRIMARY ALCOHOL HAVING ABOILING POINT BELOW THAT OF THE ALCOHOLS CONTAINED IN SAID COMPLEXMIXTURE, WHEREBY SAID SECONDARY AND TERTIARY NAPHTHENIC ALCOHOLS ARECONVERTED TO THE CORRESPONDING NAPHTHENIC ALCOHOLATES, THE SECONDARYALCOHOLATES ARE OXIDIZED TO THE CORRESPONDING KETONES BY REACTION WITHSAID NAPHTHENIC PEROXIDE AND SAID NAPHTHENIC PEROXIDE IS REDUCED TO THECORRESPONDING NAPTHENIC ALCOHOL, WHICH LAST NAMED ALCOHOL IS CONVERTEDTO THE CORRESPONDING AMPHOTERIC METAL NAPHTHENIC ALCOHOLATE BY REACTIONWITH SAID PRIMARY ALCOHOLATE, SEPARATING THE RESULTING TERITARYNAPHTHENIC ALCOHOLATES FROM THE REACTION MIXTURE AND HYDROLYZING SAIDSEPARATED TERTIARY NAPHTHENIC ALCOHOLATES TO FORM THE CORRESPONDINGTERTIARY NAPHTHENIC ALCOHOLS.